JPS6113248B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electronic circuit, and more particularly to an electronic circuit incorporating a constant voltage circuit that operates with very little power.

In order to stably operate an electronic circuit, such as an oscillation circuit, supplying a stabilized voltage is an important element, and a constant voltage circuit is necessary. In particular, in the semiconductor integrated circuit of the watch module in an electronic watch that uses a battery as a power source, taking an AgO battery as an example, the battery voltage E changes with the passage of time T as shown in the discharge characteristic curve shown in Figure 1. Therefore, the oscillation frequency of the standard time oscillation circuit changes. Therefore, it is necessary to incorporate a constant voltage circuit into an IC chip constituting a semiconductor integrated circuit so that the voltage supplied to the oscillation circuit or the like is maintained constant even if the battery voltage changes. However, conventional constant voltage circuits consume a large amount of power, and although it is relatively easy to realize a constant voltage circuit that operates with a few milliwatts of power, it is difficult to realize a constant voltage circuit that operates with only a few microwatts of power, and the entire electronic circuit It is unsuitable when trying to reduce the power consumption of the battery and extend the life of the power source battery. Further, although there is an optimum power supply voltage for electronic circuits in terms of stable operation and low power consumption, it has been difficult to supply the optimum voltage with conventional constant voltage circuits.

The present invention eliminates the above-mentioned drawbacks and provides an electronic circuit incorporating a constant voltage circuit that enables constant voltage with a power of several μW.

Furthermore, another object of the present invention is to provide an IC made of C.MOS.
The purpose of the present invention is to provide an electronic circuit that can always automatically supply the optimum power supply voltage as a constant voltage supply source for C.MOS.IC, regardless of the process conditions of the C.MOS.IC.

Next, details of the electronic circuit according to the present invention will be explained based on the illustrated embodiment.

Figure 2 shows an electronic circuit with a built-in constant voltage circuit. In the figure, 1 is a P-channel MOS
Transistors (hereinafter referred to as P.MOS), 2 are also P.MOS, and 3 are also P.MOS. 4 is an N-channel MOS transistor (hereinafter referred to as N.
MOS), 5 is also N.MOS.
Code 6 is the above P.MOS1, 2, 3, N.MOS4, 5
This is a circuit made up of C.MOS to which a constant voltage is supplied by a constant voltage circuit made up of. This circuit 6 and the constant voltage circuit described above are formed within the same IC chip 7. Reference numerals 8 and 9 are power supply terminals of the IC chip 7, which are connected to a power supply 10. P.MOS1,
2, 3, N.MOS 4, 5, and circuit 6 are interconnected as shown and connected to power supply 10 via power supply terminals 8, 9.
It is connected to the.

Next, the operation and function of this electronic circuit will be explained. P.MOS1 plays the role of limiting current
(This may be a diffused resistor, thin film resistor, etc.) P.MOS2, 3, N.MOS4 connected in series
constitutes a circuit that generates a constant reference voltage. The voltage drop of P.MOS2 is V ₂ , and P.MOS3 and N.MOS are complementary connected.
Let V ₃ and V ₄ be the voltage drops of N.MOS 5, and the voltage V _G applied to the gate of N.MOS 5 is expressed as V _G ≈V ₂ +V ₃ +V ₄ . N.MOS5 gate. If the source-to-source voltage is V _GS , the circuit 6 to which constant voltage is supplied
The power supply voltage V _AVC is expressed as V _AVC = V _G - V _GS = V ₂ + V ₃ + V ₄ - V _GS .

If the circuit 6 is a C.MOS circuit, the optimum operating voltage V _MOS of the circuit 6 is the threshold voltage of the P channel MOS transistor Vμ. Letting the threshold voltage of the N-channel MOS transistor be Vn, it is expressed as V _MOS =Vμ+Vn+α. The threshold voltages of C.MOS and complementary connected P.MOS3 and N.MOS4 in circuit 6 are approximately equal to _Vμ and _V4 , respectively, when they are manufactured in the same IC chip. . Therefore, assuming that the power supply voltage V _AVC is the optimum operating voltage V _MOS , V _AVC ≈V ₂ +Vμ+Vn-V _GS , and the above α is expressed as α≈V ₂ −V _GS .

As mentioned above, like the C.MOS that constitutes the circuit 6 in the constant voltage reference circuit, P.MOS3 and N.MOS4
Since the threshold voltage V ₂ of P.MOS2 and the gate of N.MOS5 are used. The optimal operating voltage of the circuit 6 can be easily and automatically created just by the relationship with the source-to-source voltage _VGS .

In the above embodiment, the voltage control element connected in series to the circuit 6 is composed of N.MOS5, but if the current flowing through the circuit 6 is large, a large current N.MOS5 is required. Become. Therefore, N.MOS5
must be large with a large gate width, and the IC chip 7 itself must be large. Third
The embodiment shown in the figure allows the IC chip to be made smaller even when the current flowing through the circuit 6 is large. The same reference numerals are given to the elements. The embodiment shown in FIG. 3 includes P.MOS1, 2,
3. A voltage control element to which a constant reference voltage obtained by N.MOS4 is supplied is constituted by a bipolar transistor 11. Bipolar transistor 11 is fabricated on the same chip as other MOS transistors, and an example of its structure is shown in FIG. In FIG. 4, 12 is an n-type substrate 13, 14 is a P ^- well formed in the n-type substrate 12, 15, 1
6 is the drain of P.MOS1, 2, or 3. P ⁺ region constituting the source region, 17 is an oxide film of S, O ₂ , etc., 18, 19, 20 is an electrode formed by vapor depositing Al, Au, etc., 21, 22 is the drain and source region of N.MOS4 23 is _{an oxide film such as SiO 2} ^{, 2}
4, 25, 26 are electrodes formed by vapor-depositing Al, Au, etc., and 27, 28 are bipolar electrodes. n ⁺ regions formed in the P ^- well 13 forming the collector and emitter regions of the transistor 11, 29, 30, 3
1 is an electrode formed by vapor-depositing Al, Au, etc. In addition, a circuit 6 is configured on the n-type substrate 12.
C.MOS was created at the same time. As you can see from the structure in Figure 4, bipolar. transistor 1
1 is made at the same time as P.MOS 1, 2, 3, N.MOS 4, and circuit 6, and each electrode is appropriately connected although not shown in the drawing.

According to the embodiment shown in FIG. 3 described above, the voltage control element connected in series to the circuit 6 is bipolar. Since it is composed of transistors 11, even if a large amount of current flows through the circuit 6, the entire IC chip can be made small. Note that the operation of the electronic circuit shown in FIG. 3 is similar in principle to the embodiment described above.

Although the details of the electronic circuit according to the present invention have been described above based on the illustrated embodiments, the present invention is not limited to the illustrated embodiments, and various modifications and improvements can be made.

As described above, the electronic circuit according to the present invention has a built-in constant voltage circuit that generates a reference voltage using a plurality of MOS transistors, so it is possible to stably operate a circuit that is susceptible to voltage fluctuations, and the constant voltage circuit itself can operate stably. The power consumption can be easily reduced to the μW order, and in addition, complementary connection
By using a MOS transistor in a circuit that generates a reference voltage, it is possible to easily and automatically supply the optimum operating voltage to a C.MOS circuit, especially for portable devices such as electronic watches that are powered by batteries. By applying it to equipment, it is possible to fully achieve the intended purpose, such as stable operation and miniaturization of electric power, and there are significant practical effects.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the discharge characteristic curve of an AgO battery.
FIG. 2 is a circuit diagram showing one embodiment of the electronic circuit according to the present invention, FIG. 3 is a circuit diagram showing another embodiment of the electronic circuit according to the present invention, and FIG. 4 is the electronic circuit shown in FIG. 3. FIG. 1, 2, 3...P in the circuit that generates the reference voltage
Channel MOS transistor, 4...N-channel MOS transistor in the circuit that generates the reference voltage, 5...N-channel as a voltage control element
MOS transistor, 6...Circuit consisting of C.MOS, 7...IC chip, 8, 9...Power terminal, 1
0...Power supply, 11...Vipara as a voltage control element. transistor.

Claims (1)

[Claims] 1. A first main electrode for current limiting, in which a first main electrode other than the gate is connected to one end of a power supply, and a voltage for operating the transistor is applied to the gate.
a MOS transistor, a second MOS transistor whose gate and drain are connected, and a first MOS transistor whose drains are connected together and whose respective gates are connected to the respective drains;
A CMOS transistor is connected in series between a second main electrode other than the gate of the first MOS transistor and the other end of the electrode,
The current flowing through the transistor causes the second
a reference voltage generation circuit that outputs a constant low voltage as the sum of the threshold voltages of the MOS transistor and the first CMOS transistor; a voltage control element connected to one end of the voltage control element; and a load circuit having a second CMOS transistor and connected between a second main electrode of the voltage control element and the other end of the power supply; of
The threshold voltage generated across the MOS transistor cancels out the voltage drop between the control input electrode and the second main electrode of the voltage control element, and the threshold voltage generated across the first CMOS transistor is canceled out by the threshold voltage generated across the first CMOS transistor. An electronic circuit characterized by supplying CMOS transistors.